Linux: Double Free
CVE-2026-64386 is a critical-severity double free vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 100fb7c455fa86d248b8bd7bb9de757c192870b4, 3c81dda84799f76b42aec598564316e2964440db, f1add4acb656f5a82806a1ab0e63fed3d8b1bfca as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.46% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to 100fb7c455fa86d248b8bd7bb9de757c192870b4 or 3c81dda84799f76b42aec598564316e2964440db or f1add4acb656f5a82806a1ab0e63fed3d8b1bfca or 89234773e8348918111aa15f6922b58cf3843364, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.145 or 6.12.96 or 6.18.39 or 7.1.4, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 433042a91f9373241307725b52de573933ffedbf up to, but not including, 100fb7c455fa86d248b8bd7bb9de757c192870b4; 4f1fffa2376922f3d1d506e49c0fd445b023a28e up to, but not including, 3c81dda84799f76b42aec598564316e2964440db; 4f1fffa2376922f3d1d506e49c0fd445b023a28e up to, but not including, f1add4acb656f5a82806a1ab0e63fed3d8b1bfca; 4f1fffa2376922f3d1d506e49c0fd445b023a28e up to, but not including, 89234773e8348918111aa15f6922b58cf3843364; 4f1fffa2376922f3d1d506e49c0fd445b023a28e up to, but not including, 2a88561d66eb855813cf004a0abe648bbb17de5e; 6.6.32 up to, but not including, 6.6.145; 6.8 | 100fb7c455fa86d248b8bd7bb9de757c192870b4, 3c81dda84799f76b42aec598564316e2964440db, f1add4acb656f5a82806a1ab0e63fed3d8b1bfca, 89234773e8348918111aa15f6922b58cf3843364, 2a88561d66eb855813cf004a0abe648bbb17de5e, 6.6.145 |
| Linux | Linux Kernel | 6.6.32 up to, but not including, 6.6.145; 6.8.1 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4; 6.8 | 6.6.145, 6.12.96, 6.18.39, 7.1.4 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix query_info() replay double-free A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_query_info_init() fails before the next send, cleanup retains the previous buffer type and frees that response again. Reset response bookkeeping before each attempt to prevent the stale free.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/100fb7c455fa86d248b8bd7bb9de757c192870b4
- git.kernel.org/stable/c/2a88561d66eb855813cf004a0abe648bbb17de5e
- git.kernel.org/stable/c/3c81dda84799f76b42aec598564316e2964440db
- git.kernel.org/stable/c/89234773e8348918111aa15f6922b58cf3843364
- git.kernel.org/stable/c/f1add4acb656f5a82806a1ab0e63fed3d8b1bfca
Recent Double Free vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
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